The present invention relates to refrigerated merchandisers, and more specifically to anti-sweat control for refrigerated merchandisers.
Existing refrigerated merchandisers generally include a case defining a product display area that supports and/or displays products visible and accessible through an opening in the front of the case. Some refrigerated merchandisers include doors that enclose the product display area of the case. The doors typically include one or more glass panels that allow a consumer to view the products stored inside the case.
Often, condensed moisture accumulates on one or more surfaces of the door, which obscures viewing of the product in the merchandiser. For example, moisture in a relatively warm ambient environment surrounding the merchandiser may condense on the outside surface of the glass door, or on the inside surface when the door is opened. Without heating, the condensation on the outside and inside of the glass door does not clear quickly and obscures the product in the merchandiser. Long periods of obscured product caused by condensation may detrimentally impact sales of the product.
Some doors include resistive or conductive films that are applied to the glass panel to reduce or eliminate condensation and fogging. The resistive film is connected to a power source and applies heat to the glass door via current flow through the coating. Typically, heat applied to the glass door is controlled by a controller based on a duty cycle that varies between an “on” state (i.e. heat applied to the glass door) and an “off” state to regulate the time that heat is applied to the glass door. However, when the glass door is opened during the predetermined time that the duty cycle is in the “off” state, condensation may readily form on the interior and/or exterior of the glass door.
Existing merchandisers also often include a frame heater that is connected to the frame around the doors to heat the frame. Typically, merchandisers include a single, continuous frame heater that extends across the case frame and along the mullions so that heat can be applied to all parts of the frame. While most of the condensation arises at lower areas of the frame (where the air temperature differential between the product display area and surrounding ambient air is highest), an existing frame heater applies the same amount of heat to the entire frame.